In the prior art, heavy machines for bending plates and sheets of metal have used a wedge drive system to apply pressing or cutting force. However none of the prior art machines have employed structure that provides the advantages of the present invention.
The present invention features a press brake, or other similar heavy machine for bending sheet metal or plate metal. The invention comprises a frame, a bed mounted to the frame, and a ram movably mounted to the frame. The ram has a lower tooth punch with a horizontal lower edge which interfaces with a female die which has a horizontally extending V-shaped slot. An assembly for moving the ram to and from the bed to bend the metal therebetween has first and second wedges which move between inclined ramp surfaces and slide surfaces. The movement of the wedge along the inclined surface causes the ramp to move toward and away from the bed. The dual wedges are driven by an actuator, positioned between the two wedges. The actuator can be a single unit, or double unit. The actuator is drivingly connected to the wedges to move them in first and second directions. The movement of the wedges applies force to the ram to cause it to move to and from the bed. Because the actuator is positioned between the two wedges, the force the wedges apply to the ram is applied to the two ends of the ram to thereby apply an even distribution of force across the ram. The two wedges are linked to each other by means such as link plates, so that the movement of one wedge transfers force to the second wedge to move it the same distance as the first wedge. The linkage of the two wedges provides for the horizontal edge of the ram tooth punch to be maintained parallel with the horizontal V-shaped slot of the female die, and provide for even distribution of force to the ends of the ram and across the ram. This balancing of force across the ram allows even and straight bending of the metal sheets and plates positioned between the ram and bed.
In one embodiment the actuator comprises a pair of power sources such as hydraulic or pneumatic cylinders, which have different power outputs. Each of the power sources can have a drive member extending from its exterior end to be drivingly associated with a respective wedge. This dual wedge action further allows for a balancing force across the ram. With a dual power operation, a variation of power can be more easily applied to the ram. For example one of the cylinders can be used at a certain stage of the operation such to rapidly move the ram to close engagement with the metal sheet or plate prior to bending, and then both cylinders can be used when more force more force is desired to be applied to bend the plate or sheet.
In one embodiment a single cylinder assembly can be used with the cylinder connected to the ram or frame, with a driving member extending from the cylinder to move one of the wedges. The link plates connecting the wedges cause both wedges to be moved by the single actuator. In another embodiment an actuator such as a single hydraulic or pneumatic cylinder can have a drive rod extending from each of its opposite ends to be connected to each of the wedges to move the wedges to cause the ram to move toward and away from the bed for bending operation.
With the actuator, whether it be the dual cylinder arrangement or the single cylinder arrangement, positioned between the two wedges, an even distribution of force across the ram takes place, and a compact structure is also provided. The system thus allows for application of the mechanical advantage offered by the wedges in movement of the ram relative to the bed. The placement of the actuator between the wedges further allows for lack of congestion about the ends of the machine.
Guide plates mounted to the sides of the wedges keep the wedges on track during sliding movement. The side plates have guide members extending therefrom which contact the ram and the slide members to provide for steady and smooth movement, with lubricant mounted within the engagement members.
The present invention further provides for a scaled means for adjusting the movement of the ram, which comprises a component mounted to the assembly that moves with the ram, such as on the link plate in the preferred embodiment. It has another component associated with the wedge assembly, such as being mounted on the link plate in the preferred embodiment, which component in the preferred embodiment is a cam. The means for adjusting movement further comprises a switch that is associated with the ram which has means to interact with the cam, such as through a cam arm. The cam can trip the switch to control the downward movement or depth of penetration of the ram into the bed. The means for adjusting includes a scale assembly which has a scale associated with the wedge assembly such as on the cam. The cam scale can be adjusted relative to the depth of penetration of the ram toward the bed. Another scale component extends generally horizontally relative to the wedge assembly, such as horizontally on the link plate. The cam scale can be adjusted and set relative to the other scale component to thereby set the depth of downward movement of the ram toward the bed. The two scale components can form a Vernier Scale arrangement to allow for greater accuracy in setting the position of the downward penetration. A second cam can interact with a switch to stop the ram just before contact with the sheet or plate. A third cam can activate a switch to limit upward travel of the ram.
In another embodiment, the press brake is provided with a pivoting mechanism for pivoting the ram about a pivot axis relative to said bed. A bolt passes through the second wedge to connect the second wedge to its associated guide plates, and link plates, if provided. The pivot mechanism comprises a mounting assembly for adjustably mounting said first ramp member to said frame, such that the horizontal position of said first ramp member can be selectively set prior to movement of said ram. The pivot mechanism further comprises a linear motion device operably connected between the first frame and an outer surface of the first ramp member to move the first ramp member in a first direction towards the second ramp member and in a second direction away from the second ramp member. Thus, movement of the first ramp member relative to the second ramp member causes the first ramp member to move relative to the first wedge and causes the ram to pivot about the pivot axis. The mounting assembly preferably includes a horizontal member and the first ramp member has a substantially horizontal surface opposite its angled surface. The first ramp member is slidably mounted to the horizontal member of the mounting assembly by means of an interfitting groove and tennon arrangement. The linear motion devices is preferably a bolt which passes through a leg that extends parallel to the outer surface of the first ramp member. The bolt is connected to the outer surface of the first ramp member so that it may both push and pull the first ramp member as it is rotated.
The press brake or other like bending machine of the present invention thus provides advantages over the prior art not heretofore achieved.